# -*- coding:utf-8 -*-
class Solution:
    def Fibonacci(self, n):
        # write code here
        a = [0, 1]
        if n < 2:
            return a[n]
        first = 0
        second = 1
        for i in range(2, n + 1):
            res = first + second
            frist = second
            seconmd = res
        return res


s=Solution()
m=s.Fibonacci(39)
print(m)